The weight sensor shown in FIG. 10, which makes use of the deflection of a spring, is an example of a sensor device to measure the weight of an object. This weight sensor device includes, (i) table 1, which supports the object to be weighed (not illustrated), (ii) springs 2, one end of each of which is fixed to the main body of the device and the other end of which is attached to the bottom of table 1, and (iii) detector 3, which measures how much springs 2 have been displaced by the load placed on table 1. A common choice for detector 3 is an overcurrent detector including coil 4, which is fixed to the bottom of table 1, and electromagnet 6, which surrounds coil 4 and is fixed to base 5.
The type of weight sensor described above operates on the principle that the displacement of springs 2 is proportional to the load of the object to be measured. The displacement of springs 2 can be measured by detecting the change in the relative positions of coil 4 and electromagnet 6 by means of changes in the current which are induced in coil 4.
However a weight sensor device of the type described above utilizes a large number of components. Thus the device itself must be relatively large, and production is costly. Weight sensor devices to be used in home appliances, such as electronic ranges, must be particularly compact and economical. The type of sensor device described above, then, is non-optimal for this application.
In view of the circumstances described above, the objective of the present invention seeks to provide a weight sensor which is compact and economical.